In recent years, network devices (e.g., printers, scanners and copying machines capable of connecting to networks) are rapidly becoming popular as network infrastructure is deployed.
In order to use a network device from a client apparatus (client PC) such as PC (Personal Computer), various settings are required. For example, it is required to install driver software for the network device into the PC. It is also required to know the IP address of the network device, the printer port, the print protocol to be used and the like and to set them to the driver software.
Recently, technologies for searching a network device or service connected to a network, such as Universal Plug and Play (UPnP) proposed by Microsoft Corporation, have been developed.
According to UPnP version 1.0, a client apparatus transmits a search packet to which a multicast address is set as the destination address of the packet. Having received the search packet, the network device returns to the client apparatus a response packet including its own address information and the like. In this way, the client apparatus can acquire setting information of the network device.
A technology for accumulating setting information about network devices in a search server in advance has also been proposed (see, Japanese Patent Laid-Open No. 2000-312222).
Of course, as described above, transmitting a search packet as a multicast packet facilitates searching for a network device. However, when the number of the clients or the network devices is increased, search and response packets may cause network congestion. In addition, process load for the clients and the network devices will also be increased.
On the other hand, if a proxy server for transmitting the response packet is provided in place of the network device, process load for the network device is reduced. However, in a network system in which both a network device and a proxy server respond to a search packet, both the network device and the proxy server may transmit response packets to respond to a multicast search packet. This can not reduce the network congestion.